WO2012003649A1

WO2012003649A1 - Aluminum electrolytic cell having cathode carbon block with columnar protrusions embedded on its upper surface

Info

Publication number: WO2012003649A1
Application number: PCT/CN2010/075575
Authority: WO
Inventors: 冯乃祥
Original assignee: 沈阳北冶冶金科技有限公司
Priority date: 2010-07-08
Filing date: 2010-07-30
Publication date: 2012-01-12
Also published as: CN101864580B; CA2804944A1; US20130112549A1; CN101864580A; EP2592176A1

Abstract

An aluminum electrolytic cell in which columnar protrusions are embedded onto the upper surfaces of a cathode carbon block is disclosed, wherein, the cathode carbon block consists of a cathode carbon block substrate and columnar protrusions on the upper surface of the substrate, and the columnar protrusions are embedded onto the upper surface of the cathode carbon block substrate. By embedding columnar protrusions onto the upper surface of the cathode carbon block substrate, it is allowable to have multiple choices for substrate materials of the cathode carbon block and their production methods. There is a merit of making the cathode carbon block with less processing amount and lower cost. The flow speed and fluctuation of the aluminum liquid is remarkably reduced in the electrolytic cell and the cell is normally operated at lower cell voltage.

Description

Aluminum electrolytic cell with cylindrical protrusion on top surface of cathode carbon block

The invention belongs to the technical field of aluminum electrolysis, and particularly relates to an aluminum electrolysis cell with a cylindrical protrusion on the upper surface of a cathode carbon block. Background technique

At present, industrial pure aluminum is obtained by the method of cryolite-alumina melting salt electrolysis, and the anode of the electrolytic cell used is a combination of anode carbon blocks prepared from calcined petroleum coke. The cathode of the electrolytic cell is also assembled by carbon blocks. The bottom of each cathode carbon block of the electrolytic cell is provided with a steel bar. Both ends of the steel bar protrude from two sides of the electrolytic cell and are connected with the cathode bus bar, and the cathode carbon block and The carbon blocks are bonded between the cathode carbon blocks.

At present, the cathode carbon block of the aluminum electrolytic cell used in the industry is mostly made of high temperature calcined anthracite. In order to increase the conductivity of the cathode carbon block and the corrosion resistance of sodium and electrolyte, the electric calcined anthracite block is also widely used. Add artificial graphite to the ingredients. The content of artificial graphite generally accounts for about 30~50% of the total cathode carbon block aggregate, which is called semi-graphitic cathode carbon block. It is also useful for all-graphite carbon block. The so-called all-graphite cathode carbon block is made. The bone pellet formulation (including powder pellets) of the cathode carbon block is 100% artificial graphite. In addition, in order to make the cathode carbon block have a smaller electrical resistance and better resistance to sodium and electrolyte corrosion so that the cathode of the electrolytic cell has a smaller cathode voltage drop and a higher tank life, many larger capacity electrolysis The trough also begins to use graphitized cathode carbon blocks or semi-graphitized cathode carbon blocks made entirely of petroleum coke. However, after the semi-graphitic, graphite and graphitized cathode carbon blocks are used in the cathode carbon block of the aluminum electrolytic cell, the strength and the aluminum liquid scouring and abrasion in the electrolytic cell are increased as the content of the artificial graphite component in the cathode carbon block increases. The ability is getting worse.

In 2007, Feng Naixiang of Northeastern University invented a special-shaped cathode structure aluminum electrolysis cell. This cathode structure aluminum electrolysis cell is characterized by a convex structure on the surface of the cathode carbon block. The convex structure has the functions of greatly reducing the flow rate of the aluminum liquid and reducing the fluctuation of the aluminum liquid, and increasing the stability of the aluminum liquid in the electrolytic cell, so that the cell voltage of the electrolytic cell is greatly reduced, and the current efficiency is further improved, and the aluminum electrolytic cell is greatly reduced. The effect of power consumption.

An important technical requirement for the cathode of the abnormal-shaped cathode structure aluminum electrolytic cell is that the protrusion on the cathode carbon block of the electrolytic cell must have a good ability to resist the erosion of the cathode aluminum liquid, and the conventional calcined anthracite is the cathode of the main material. The carbon block has strong anti-cathode aluminum liquid scouring ability. The practice of series production of heterogeneous cathode structure electrolyzers shows that the anthracite block containing 30% artificial graphite with a convex structure on the cathode surface has a convex consumption on the cathode surface. It can be reduced to 10mm/year, and the height of the cathode protrusion is 110mm. Therefore, the surface of the cathode carbon block made of anthracite as the main aggregate material has a convex structure which can satisfy the life of the aluminum electrolytic cell to the cathode carbon block. Requirements.

However, for graphite cathode carbon blocks with artificial graphite as the main aggregate material, or graphitized cathode carbon blocks, the resistance to aluminum liquid scouring is far less than that of cathode carbon blocks with anthracite as the main aggregate material. Aluminum scouring ability, the latter It is several times the former. Therefore, the cathode carbon block having a convex structure on the surface of the graphite or graphitization material does not satisfactorily satisfy the requirement of the cathode surface of the shaped cathode structure electrolytic cell. In addition, the cathode carbon block of the aluminum electrolytic cell whose surface has a lateral convex structure perpendicular to the longitudinal direction of the cathode carbon block of the electrolytic cell not only has a large processing amount, but also consumes a large amount of material, so that the material cost and the cost of processing are increased. Increased, higher production costs.

Summary of the invention

In view of the above problems, the present invention provides an aluminum electrolytic cell with a cylindrical protrusion on the upper surface of a cathode carbon block, through a surface of anthracite carbon block, or a fully graphite, semi-graphitized or fully graphitized cathode carbon block. The upper surface of the base body is inlaid with a convex structure, so that the cathode carbon block has a strong anti-aluminum liquid scouring ability.

The aluminum electrolytic cell with the cylindrical carbon protrusion on the upper surface of the cathode carbon block of the invention comprises a groove shell, a groove lining refractory insulation material, a side carbon brick, a cathode carbon block and a cathode steel rod, and each cathode carbon block is filled between There is a carbon paste, and each cathode carbon block and the side carbon brick are tamped with a carbon paste; wherein the cathode carbon block is composed of a cathode carbon block base and a cylindrical protrusion on the upper surface thereof, and the columnar protrusion is embedded in the cathode carbon block. The upper surface of the substrate.

A graphite paste is filled between the above-mentioned cylindrical projections and the cathode carbon block base, and the graphite paste is a paste obtained by mixing a thermosetting resin and a graphite powder.

The cathode carbon block substrate is a rectangular parallelepiped having a groove on its upper surface, and the cylindrical protrusion is embedded in the upper surface of the cathode carbon block base through the groove.

The above-mentioned cylindrical protrusion is a rectangular parallelepiped or a cylinder.

The above-mentioned cylindrical protrusion is formed by calcining anthracite, or a mixture of calcined anthracite and artificial graphite, or artificial graphite, crushed into aggregate and asphalt, and then calcined, or processed by artificial graphite electrode and graphite block. When the cylindrical protrusion is a cylinder, the side surface of the portion inserted into the cathode carbon block base is machined with an external thread.

In the above electrolytic cell, when the cylindrical protrusion is a rectangular parallelepiped, the length direction of the cylindrical protrusion is perpendicular to the longitudinal direction of the cathode carbon block base, and the cylindrical convexity is under the condition that the width of the cathode carbon block base is 50 to 70 cm. The length is 21~35cm and the width is 17~30cm. The difference between the height of the cylindrical protrusion and the upper surface of the cathode carbon block is 9~15cm. When the width of the cathode carbon block is increased, the length of the cylindrical protrusion is as follows. The proportion of the increase in the width of the cathode carbon block matrix increases.

In the above electrolytic cell, when the cylindrical protrusion is a cylinder, when the width of the cathode carbon block substrate is 50 to 70 cm, the diameter of the cylindrical protrusion is 17 to 35 cm, and the cylindrical protrusion and the cathode carbon block are on the substrate. The height difference of the surface is 9 to 15 cm. When the width of the cathode carbon block is increased, the diameter of the columnar protrusion increases in proportion to the increase in the width of the cathode carbon block substrate.

In the above electrolytic cell, the columnar protrusions are arranged in two or three rows along the length direction of the upper surface of the cathode carbon block substrate, and the adjacent two rows of columnar protrusions are staggered; the width of the cathode carbon block substrate is 50 to 70 cm. Under the condition, the spacing between two adjacent cylindrical protrusions in the same row of cylindrical protrusions is 17~35cm, and the spacing between adjacent cylindrical protrusions of different rows on the same cathode carbon block is 5~20cm, and the distance between the two cylindrical protrusions adjacent to the aluminum outlet is 30~70cm.

The above-mentioned cylindrical protrusion has a depth of 5 to 10 cm in the cathode carbon block base.

The method for preparing the cathode carbon block of the aluminum electrolytic cell of the present invention is carried out as follows:

1. There are two methods for preparing a cathode carbon block matrix:

(1) The cathode carbon block substrate is produced by extrusion method. When the cross section of the substrate is a regular rectangular surface, the green body of the cathode carbon block matrix is produced, and is calcined at 1100~1300 °C to form an anthracite or graphite cathode carbon block. The substrate is firstly calcined at 1100~1300 °C and then subjected to high temperature heat treatment at 2300~2500 °C to form a semi-graphitized cathode carbon block matrix, and then the position of the upper surface of the cathode carbon block substrate is required to be embedded with a columnar protrusion. Processing into a circular pit having a depth of 5 - 10 cm, and machining an internal thread on the sidewall of the pit, the internal thread cooperating with the external thread of the cylindrical protrusion of the cylinder;

2 When the cathode carbon block base body is produced by vibration molding or compression molding, the bottom surface of the weight on the material used in the vibration molding die is changed to a conventional plane to have a convex structure, or a material in the mold during molding. The bottom surface of the stamper is changed to a conventional plane having a convex structure on the surface thereof; thus, after the cathode carbon block substrate is vibrated or molded, the upper surface of the cathode carbon block base body having vibration molding or compression molding has a pit for arranging the column-shaped protrusions; wherein the bottom surface of the weight of the material in the mold or the position of the convex structure on the bottom surface of the mold material in the mold and the cylindrical surface of the cathode carbon block are inlaid with cylindrical protrusions Corresponding to the position; the shape of the convex structure is consistent with the shape of the pit groove to be embedded with the columnar protrusion on the upper surface thereof to be vibrated or molded; the depth of the pit is 5-10 cm; In the case of an anthracite cathode carbon block substrate, a graphite cathode carbon block substrate or a semi-graphite cathode carbon block substrate, the cathode carbon block substrate green body is fired at 1100 to 1300 ° C, Forming a cathode carbon block substrate with a pit; when the cathode carbon block substrate is a graphitized or semi-graphitized cathode carbon block substrate, the roasting method and the method and method for forming the pits and the method of burning and forming the pit The method of the tank is the same. After calcination, the high temperature treatment is carried out in a graphitization furnace at 2300~3000 °C to prepare a semi-graphitized or fully graphitized cathode carbon block matrix; the pits on the upper surface of the cathode carbon block substrate are divided into a circular pit and a square pit; when the pit is circular, the inner wall of the pit is machined with an internal thread which cooperates with the external thread of the cylindrical protrusion of the cylinder; when the pit is a square pit When the inner wall has at least 4 circular pits having a diameter of not less than 5 mm and a depth of not less than 10 mm;

2. The graphite paste is prepared by mixing the thermosetting resin and the graphite powder, and the mixing ratio is required to be mixed into a paste; the graphite paste is filled into the pit; then the cylindrical protrusion is filled into the pit, wherein the column is shaped When the protrusion is a rectangular parallelepiped, the pit is also a square pit. The length and width of the pit are larger than the length and width of the column protrusion by l~10mm, and the rectangular columnar protrusion is vertically pressed into the pit; When the shape is cylindrical, the groove is circular, the side wall is machined with internal threads; the external thread on the cylindrical protrusion cooperates with the internal thread in the groove, the cylindrical protrusion is screwed into the groove, the internal thread and the outer There is also graphite paste filling between the thread gaps; when the columnar protrusions enter the pit, a part of the graphite paste will be squeezed out from the gap between the protrusions and the pits, and accumulated on the cathode carbon block substrate. Where the surface engages the stud bumps. During the calcination of the aluminum electrolytic cell, the thermosetting resin in the graphite paste discharges the volatiles to carbonize, and the cylindrical protrusions are more closely connected to the cathode carbon block substrate.

The working condition of the aluminum electrolysis cell with the cylindrical protrusion on the upper surface of the cathode carbon block of the invention is: the cylindrical protrusion of the cathode carbon block is immersed in the aluminum liquid, and the aluminum liquid is an electrolyte melt. The height of the aluminum liquid surface is higher than the upper surface of the protrusion, which is l~10cm after the aluminum is discharged, and the working voltage of the electrolytic cell is between 3.5~3.9V.

The invention inserts a cylindrical protrusion on the cathode carbon block base, so that the entire cathode carbon block can freely select the material of the cathode carbon block base while reducing the fluctuation of the filtrate, thereby achieving the enhancement of the working ability of the cathode carbon block and improving. The effect of the life of the cathode carbon block; at the same time, the method of embedding the columnar protrusion on the cathode carbon block base has the advantages of small processing amount and low cost compared with the original method for directly preparing the protrusion on the cathode carbon block. advantage. The cathode carbon block aluminum electrolysis cell with the cylindrical protrusions embedded in the surface of the invention has been tested to show that the working performance is stable, and the flow rate and fluctuation of the aluminum liquid can be more effectively reduced, so that the cell voltage can work normally at a lower condition.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing an aluminum electrolytic cell according to a first embodiment of the present invention.

Figure 2 is a cross-sectional view taken along line B-B of Figure 1.

Fig. 3 is a schematic cross-sectional view showing the aluminum electrolytic cell of the second embodiment of the present invention.

Figure 4 is a cross-sectional view taken along line B-B of Figure 3.

Figure 5 is a schematic cross-sectional view showing an aluminum electrolytic cell according to Embodiment 3 of the present invention.

Figure 6 is a cross-sectional view taken along line B-B of Figure 5.

Figure 7 is a schematic cross-sectional view showing an aluminum electrolytic cell of Embodiment 4 of the present invention.

Figure 8 is a cross-sectional view taken along line B-B of Figure 7.

Figure 9 is a schematic cross-sectional view showing an aluminum electrolytic cell according to Embodiment 5 of the present invention.

Figure 10 is a cross-sectional view taken along line B-B of Figure 9

In the figure, 1, the shell, 2, the side carbon brick, 3, the cathode carbon block base, 4, the columnar protrusion, 5, the side carbon paste, 6, the cathode steel rod, 7, the groove bottom refractory insulation material, 8 , Refractory insulation material on the side of the trough, 9, graphite paste, 10, carbon paste between the cathode carbon block.

Detailed ways

In the embodiment of the invention, the cathode carbon block substrate has a width of 50 to 70 cm.

The graphite paste in the embodiment of the present invention is prepared by mixing a thermosetting resin and graphite powder, and the ratio is required to be mixed to form a paste.

The preparation method of the cathode carbon block in the embodiment of the invention is: 1. There are two methods for preparing a cathode carbon block matrix:

2. The graphite paste is prepared by mixing the thermosetting resin and the graphite powder, and the mixing ratio is required to be mixed into a paste; the graphite paste is filled into the pit; then the cylindrical protrusion is filled into the pit, wherein the column is shaped When the protrusion is a rectangular parallelepiped, the pit is also a square pit. The length and width of the pit are larger than the length and width of the column protrusion by l~10mm, and the rectangular columnar protrusion is vertically pressed into the pit; When the shape is cylindrical, the groove is circular, the side wall is machined with internal threads; the external thread on the cylindrical protrusion cooperates with the internal thread in the groove, the cylindrical protrusion is screwed into the groove, the internal thread and the outer There is also graphite paste filling between the thread gaps; when the columnar protrusions enter the pit, a part of the graphite paste will be squeezed out from the gap between the protrusions and the pits, and accumulated on the cathode carbon block substrate. Where the surface engages the stud bumps.

Example 1

The aluminum electrolytic cell with the cylindrical protrusion on the upper surface of the cathode carbon block is shown in Fig. 1, and the BB surface sectional view is shown in Fig. 2. The electrolytic cell includes the groove shell 1, the groove lining refractory heat insulating material, and the side carbon brick 2 , cathode carbon block and cathode steel rod 6, between each cathode carbon block Filled with carbon tamping paste 10 between cathode carbon blocks, each cathode carbon block and side carbon bricks are tamped with a side carbon 5 paste; wherein the cathode carbon block is composed of a cathode carbon block base 3 and a column on its upper surface The convex protrusions 4 are formed, and the cylindrical projections 4 are embedded in the upper surface of the cathode carbon block base 1. The groove-lined refractory heat insulating material comprises a groove bottom refractory heat insulating material 7 and a groove side refractory heat insulating material 8, and a side carbon brick 2 is provided inside the side carbon brick 2.

The cathode carbon block base 3 is a rectangular parallelepiped having a groove on its upper surface, and the cylindrical protrusion 4 is embedded in the upper surface of the cathode carbon block base 3 through a groove; the cylindrical protrusion 4 is a rectangular parallelepiped, a cylindrical protrusion 4 and a cathode A graphite paste 9 is filled between the carbon block substrates 3.

The longitudinal direction of the cylindrical projection is perpendicular to the longitudinal direction of the cathode carbon block base. The length of the cylindrical projection is 30 cm and the width is 20 cm, and the height difference between the cylindrical projection and the upper surface of the cathode carbon block substrate is 9 cm.

The columnar protrusions are arranged in two rows along the length direction of the upper surface of the cathode carbon block substrate, and the columnar protrusions are evenly distributed on the upper surface of the cathode carbon block substrate, and the adjacent two rows of columnar protrusions are staggered; the same row of columnar protrusions The spacing between adjacent two cylindrical protrusions is 17~35cm, and the spacing between adjacent cylindrical protrusions of different rows on the same cathode carbon block is 20cm, and two columns adjacent to the aluminum outlet The spacing between the projections is 60 cm.

The above-mentioned cylindrical protrusions are formed by calcining anthracite and then calcined.

The working conditions of the aluminum electrolytic cell with the cylindrical protrusion on the upper surface of the cathode carbon block during electrolytic production of metal aluminum are as follows: The column shape of the cathode carbon block is immersed in the aluminum liquid, and the aluminum liquid is above the electrolyte melt, the aluminum liquid surface The height is higher than the upper surface of the protrusion, which is l~10cm after the aluminum is discharged, and the working voltage of the electrolytic cell is between 3.5~3.9V.

Example 2

The aluminum electrolytic cell with the cylindrical protrusion on the upper surface of the cathode carbon block is shown in Fig. 3, and the B-B surface sectional view is shown in Fig. 4. The difference between the electrolytic cell structure and the first embodiment is as follows:

The columnar protrusions are arranged in three rows along the length direction of the upper surface of the cathode carbon block substrate, the length of the columnar protrusion is 21 cm, the width is 19 cm, and the height difference between the columnar protrusion and the upper surface of the cathode carbon block substrate is 10 cm; The spacing between two adjacent cylindrical protrusions in the cylindrical protrusion is 25 cm, and the spacing of adjacent column protrusions of different rows on the same cathode carbon block is 5 cm, and two columns adjacent to the aluminum outlet The spacing between the shaped projections is 50 cm.

The cylindrical protrusions are made of a mixture of calcined anthracite and artificial graphite.

Example 3

The aluminum electrolytic cell with the cylindrical protrusion on the upper surface of the cathode carbon block is shown in Fig. 5, and the BB surface sectional view is shown in Fig. 6. The structure of the electrolytic cell is the same as that in the first embodiment, and the difference lies in: The cylindrical protrusion is a cylinder. Under the condition that the width of the cathode carbon block base is 50-70 cm, the diameter of the cylindrical protrusion is 25 cm, and the height difference between the cylindrical protrusion and the upper surface of the cathode carbon block substrate is llcm. The spacing between two adjacent cylindrical protrusions in the cylindrical protrusion is 30 cm, and the spacing between adjacent cylindrical protrusions of different rows on the same cathode carbon block is 20 cm, and two adjacent to the aluminum outlet The spacing between the cylindrical projections was 40 cm.

The cylindrical protrusion is formed by molding an artificial graphite material and then calcining it.

Example 4

The aluminum electrolytic cell with the cylindrical protrusion on the upper surface of the cathode carbon block is shown in Fig. 7, and the B-B surface sectional view is shown in Fig. 8. The structure of the electrolytic cell is the same as that in the third embodiment, and the difference lies in:

The columnar protrusions are arranged in three rows along the length direction of the upper surface of the cathode carbon block substrate, the diameter of the columnar protrusion is 17 cm, and the height difference between the columnar protrusion and the upper surface of the cathode carbon block substrate is llcm, and the same row of columnar protrusions The spacing between two adjacent cylindrical protrusions is 19 cm, and the spacing of adjacent columnar protrusions of different rows on the same cathode carbon block is 5 cm, and two cylindrical protrusions adjacent to the aluminum outlet are simultaneously The spacing between the two is 30 cm.

The cylindrical protrusions are made of artificial graphite electrodes and graphite blocks.

Example 5

The aluminum electrolytic cell with the cylindrical protrusion on the upper surface of the cathode carbon block is shown in Fig. 9, and the B-B surface sectional view is shown in Fig. 10. The difference between the electrolytic cell structure and the first embodiment is as follows:

Under the condition that the width of the cathode carbon block substrate was 66 cm, the length of the stud bump was 30 cm and the width was 23 cm, and the height difference between the stud bump and the upper surface of the cathode carbon block substrate was llc m. The spacing between two adjacent cylindrical protrusions in the same row of cylindrical protrusions is 35 cm, and the spacing between adjacent cylindrical protrusions of different rows on the same cathode carbon block is 10 cm, and two adjacent to the aluminum outlet The spacing between the cylindrical protrusions is 70 cm.

Claims

Claim

1. An aluminum electrolytic cell with a cylindrical protrusion on a surface of a cathode carbon block, comprising a cathode carbon block; wherein: the cathode carbon block is composed of a cathode carbon block base and a plurality of columnar protrusions, and a column shape The protrusion is embedded in the upper surface of the cathode carbon block substrate.

2 . The aluminum electrolytic cell with a cylindrical protrusion on the upper surface of the cathode carbon block according to claim 1 , wherein the cylindrical protrusion and the cathode carbon block base are filled with a graphite paste, The graphite paste is a paste obtained by mixing a thermosetting resin and graphite powder.

3 . The aluminum electrolytic cell with a cylindrical protrusion on the upper surface of the cathode carbon block according to claim 1 , wherein the cathode carbon block base body is a rectangular parallelepiped, and the upper surface thereof is provided with a groove and a cylindrical convex shape. It is embedded in the upper surface of the cathode carbon block substrate through a groove.

4. The aluminum electrolytic cell with a cylindrical protrusion on the upper surface of the cathode carbon block according to claim 1, wherein the cylindrical protrusion is a rectangular parallelepiped or a cylinder.

5 . The aluminum electrolytic cell with a cylindrical protrusion on the upper surface of the cathode carbon block according to claim 1 , wherein the cylindrical protrusion is composed of calcined anthracite or a mixture of calcined anthracite and artificial graphite. Material, or artificial graphite is crushed into aggregate and asphalt, and then calcined, or processed by artificial graphite electrode and graphite block.

The aluminum electrolytic cell with a cylindrical protrusion on the upper surface of the cathode carbon block according to claim 1, wherein the method for preparing the cathode carbon block with the columnar protrusion on the upper surface is as follows:

(1) Two methods are used to prepare the cathode carbon block matrix:

2 When the cathode carbon block base body is produced by vibration molding or compression molding, the bottom surface of the weight on the material used in the vibration molding die is changed to a conventional plane to have a convex structure, or a material in the mold during molding. The bottom surface of the stamper is changed to a conventional plane having a convex structure on the surface thereof; thus, after the cathode carbon block substrate is vibrated or molded, the upper surface of the cathode carbon block base body having vibration molding or compression molding has a pit for arranging the column-shaped protrusions; wherein the bottom surface of the weight of the material in the mold or the position of the convex structure on the bottom surface of the mold material in the mold and the cylindrical surface of the cathode carbon block are inlaid with cylindrical protrusions Corresponding to the position; the shape of the convex structure is consistent with the shape of the pit groove to be embedded with the columnar protrusion on the upper surface thereof to be vibrated or molded; the depth of the pit is 5-10 cm; No When the bituminous coal cathode carbon block base, the graphite cathode carbon block base or the semi-graphite cathode carbon block base body, the cathode carbon block base body blank is fired at 1100~1300 ° C to form a cathode carbon block base body with a pit; When the cathode carbon block substrate is a graphitized or semi-graphitized cathode carbon block substrate, the roasting method and the method for forming the pit are the same as the method for the method of firing and the method for forming the pit, and after calcination in the graphitization furnace The high temperature treatment is carried out at 2300~3000 °C to form a semi-graphitized or fully graphitized cathode carbon block matrix; the pits on the upper surface of the cathode carbon block substrate are divided into circular pits and square pits; When it is circular, the inner wall of the pit is machined with an internal thread which cooperates with the external thread of the cylindrical protrusion of the cylinder; when the pit is a square pit, the inner wall has at least 4 diameters of not less than 5 mm. , a round pit with a depth of not less than 10 mm;

(2) A graphite paste is prepared by mixing a thermosetting resin and a graphite powder, and the mixing ratio is required to be mixed into a paste; the graphite paste is filled into the pit; then the columnar protrusion is placed in the pit, wherein the column is When the convex shape is a rectangular parallelepiped, the pit is also a square pit. The length and width of the pit are larger than the length and width of the cylindrical protrusion by l~10 mm, and the rectangular cylindrical protrusion is vertically pressed into the pit; When the shape is cylindrical, the groove is circular, and the side wall is machined with internal threads: the external thread on the cylindrical protrusion cooperates with the internal thread in the groove, the cylindrical protrusion is screwed into the groove, the internal thread and There is also graphite paste filling between the external thread gaps; when the cylindrical protrusions enter the pit, a part of the graphite paste will be squeezed out from the gap between the protrusions and the pits, and accumulated in the cathode carbon block matrix. Where the upper surface engages the stud bumps.